RESUMO
UHRF1 facilitates the establishment and maintenance of DNA methylation patterns in mammalian cells. The establishment domains are defined, including E3 ligase function, but the maintenance domains are poorly characterized. Here, we demonstrate that UHRF1 histone- and hemimethylated DNA binding functions, but not E3 ligase activity, maintain cancer-specific DNA methylation in human colorectal cancer (CRC) cells. Disrupting either chromatin reader activity reverses DNA hypermethylation, reactivates epigenetically silenced tumor suppressor genes (TSGs), and reduces CRC oncogenic properties. Moreover, an inverse correlation between high UHRF1 and low TSG expression tracks with CRC progression and reduced patient survival. Defining critical UHRF1 domain functions and its relationship with CRC prognosis suggests directions for, and value of, targeting this protein to develop therapeutic DNA demethylating agents.
Assuntos
Proteínas Estimuladoras de Ligação a CCAAT/metabolismo , Neoplasias Colorretais/enzimologia , Metilação de DNA , Epigênese Genética , Ubiquitina-Proteína Ligases/metabolismo , Animais , Proteínas Estimuladoras de Ligação a CCAAT/genética , Células CACO-2 , Neoplasias Colorretais/genética , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Ilhas de CpG , Feminino , Regulação Neoplásica da Expressão Gênica , Células HCT116 , Células HT29 , Histonas/genética , Histonas/metabolismo , Humanos , Masculino , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Camundongos Nus , Camundongos SCID , Mutação , Metástase Neoplásica , Dedos de Zinco PHD , Prognóstico , Fatores de Tempo , Ubiquitina-Proteína Ligases/genéticaRESUMO
We addressed the precursor role of aging-like spontaneous promoter DNA hypermethylation in initiating tumorigenesis. Using mouse colon-derived organoids, we show that promoter hypermethylation spontaneously arises in cells mimicking the human aging-like phenotype. The silenced genes activate the Wnt pathway, causing a stem-like state and differentiation defects. These changes render aged organoids profoundly more sensitive than young ones to transformation by BrafV600E, producing the typical human proximal BRAFV600E-driven colon adenocarcinomas characterized by extensive, abnormal gene-promoter CpG-island methylation, or the methylator phenotype (CIMP). Conversely, CRISPR-mediated simultaneous inactivation of a panel of the silenced genes markedly sensitizes to BrafV600E-induced transformation. Our studies tightly link aging-like epigenetic abnormalities to intestinal cell fate changes and predisposition to oncogene-driven colon tumorigenesis.
Assuntos
Adenocarcinoma/genética , Envelhecimento/genética , Transformação Celular Neoplásica/genética , Neoplasias do Colo/genética , Metilação de DNA , Inativação Gênica , Mutação , Proteínas Proto-Oncogênicas B-raf/genética , Células-Tronco/enzimologia , Via de Sinalização Wnt/genética , Adenocarcinoma/enzimologia , Adenocarcinoma/patologia , Fatores Etários , Envelhecimento/metabolismo , Envelhecimento/patologia , Animais , Transformação Celular Neoplásica/metabolismo , Transformação Celular Neoplásica/patologia , Neoplasias do Colo/enzimologia , Neoplasias do Colo/patologia , Regulação Neoplásica da Expressão Gênica , Predisposição Genética para Doença , Humanos , Camundongos Endogâmicos NOD , Camundongos Mutantes , Camundongos SCID , Fenótipo , Proteínas Proto-Oncogênicas B-raf/metabolismo , Células-Tronco/patologia , Fatores de Tempo , Técnicas de Cultura de TecidosRESUMO
Overall shared DNA methylation patterns between senescence (Sen) and cancers have led to the model that tumor-promoting epigenetic patterns arise through senescence. We show that transformation-associated methylation changes arise stochastically and independently of programmatic changes during senescence. Promoter hypermethylation events in transformation involve primarily pro-survival and developmental genes, similarly modified in primary tumors. Senescence-associated hypermethylation mainly involves metabolic regulators and appears early in proliferating "near-senescent" cells, which can be immortalized but are refractory to transformation. Importantly, a subset of transformation-associated hypermethylated developmental genes exhibits highest methylation gains at all age-associated cancer risk states across tissue types. These epigenetic changes favoring cell self-renewal and survival, arising during tissue aging, are fundamentally important for stratifying cancer risk and concepts for cancer prevention.
Assuntos
Transformação Celular Neoplásica/genética , Ilhas de CpG/genética , Metilação de DNA/genética , Epigênese Genética/genética , Animais , Senescência Celular/genética , Humanos , Camundongos , Camundongos SCID , Neoplasias/genética , Regiões Promotoras Genéticas/genética , RiscoRESUMO
An oncogenic role for CHD4, a NuRD component, is defined for initiating and supporting tumor suppressor gene (TSG) silencing in human colorectal cancer. CHD4 recruits repressive chromatin proteins to sites of DNA damage repair, including DNA methyltransferases where it imposes de novo DNA methylation. At TSGs, CHD4 retention helps maintain DNA hypermethylation-associated transcriptional silencing. CHD4 is recruited by the excision repair protein OGG1 for oxidative damage to interact with the damage-induced base 8-hydroxydeoxyguanosine (8-OHdG), while ZMYND8 recruits it to double-strand breaks. CHD4 knockdown activates silenced TSGs, revealing their role for blunting colorectal cancer cell proliferation, invasion, and metastases. High CHD4 and 8-OHdG levels plus low expression of TSGs strongly correlates with early disease recurrence and decreased overall survival.
Assuntos
Autoantígenos/genética , Neoplasias Colorretais/genética , Metilação de DNA , Repressão Epigenética , Regulação Neoplásica da Expressão Gênica , Inativação Gênica , Genes Supressores de Tumor , Complexo Mi-2 de Remodelação de Nucleossomo e Desacetilase/genética , 8-Hidroxi-2'-Desoxiguanosina , Animais , Autoantígenos/metabolismo , Movimento Celular , Proliferação de Células , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Neoplasias Colorretais/enzimologia , Neoplasias Colorretais/patologia , Neoplasias Colorretais/cirurgia , DNA (Citosina-5-)-Metiltransferases/genética , DNA (Citosina-5-)-Metiltransferases/metabolismo , Dano ao DNA , DNA Glicosilases/genética , DNA Glicosilases/metabolismo , Desoxiguanosina/análogos & derivados , Desoxiguanosina/metabolismo , Intervalo Livre de Doença , Regulação para Baixo , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Células HCT116 , Antígenos de Histocompatibilidade/genética , Antígenos de Histocompatibilidade/metabolismo , Histona-Lisina N-Metiltransferase/genética , Histona-Lisina N-Metiltransferase/metabolismo , Humanos , Estimativa de Kaplan-Meier , Complexo Mi-2 de Remodelação de Nucleossomo e Desacetilase/metabolismo , Camundongos Endogâmicos BALB C , Camundongos Nus , Metástase Neoplásica , Estresse Oxidativo , Modelos de Riscos Proporcionais , Interferência de RNA , Receptores de Quinase C Ativada , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Fatores de Tempo , Transcrição Gênica , Transfecção , Proteínas Supressoras de TumorRESUMO
The gene hypermethylated in cancer-1 (HIC1) encodes a zinc-finger transcription factor that belongs to a group of proteins known as the POZ family. HIC1 is hypermethylated and transcriptionally silent in several types of human cancer. Homozygous disruption of Hic1 impairs development and results in embryonic and perinatal lethality in mice. Here we show that mice disrupted in the germ line for only one allele of Hic1 develop many different spontaneous malignant tumors, including a predominance of epithelial cancers in males and lymphomas and sarcomas in females. The complete loss of Hic1 function in the heterozygous mice seems to involve dense methylation of the promoter of the remaining wild-type allele. We conclude that HIC1 is a candidate tumor-suppressor gene for which loss of function in both mouse and human cancers is associated only with epigenetic modifications.
